Lamination with protective films is commonly used to protect print substrates. The laminated product not only looks nice, but also protects from the aging process and environment. Such products typically include a media or substrate such as paper (documents, posters and photographs), polyvinyl chloride (PVC) plastic cards (credit cards, driver's license, or other identification cards), cardboard (packaging or posters), foam-board (presentation, exhibition or display pieces), etc., laminated on one or both sides with a transparent plastic film. The film can be glossy or matte or with a particular texture depending upon the application. Examples of such products include menus, book covers, presentation folders, boxes, video cassette cases, record and CD jackets and displays for stores and exhibition.
Items to be laminated can be laminated using one-sided or two-sided laminations. Also, the laminating and mounting process can be accomplished using heat and pressure (thermal lamination process) or pressure alone (pressure sensitive process). Usually the adhesive employed dictates the process to be used.
For certain applications, it is desired to mount a first substrate onto a supportive rigid second substrate, such as foam board, GATORBOARD®, PVC board, SYNTRA®, matt board, illustration board or cardboard (e.g., 24 pt. board). Typically, the first substrate is first laminated (using one- or two-sided lamination), then adhered onto the second substrate. This laminating and/or mounting process can be accomplished using heat or pressure or a combination thereof by using wet adhesives, thermal lamination and/or pressure sensitive adhesives.
In the thermal lamination process, the film, generally polypropylene, polyester, vinyl or nylon, has a layer of heat activated adhesive on one side. The adhesive side is placed against the article or articles to be laminated. The articles to be laminated take two forms: precut and continuous. Usually, the items to be laminated are precut, separated and stacked and then fed automatically or manually into the laminating machine. In the alternative, the articles are continuous or in roll form and fed into the machine. Once laminated, the product is cut at its ends (the leading edge and the trailing edge) and slit along its sides (the side margins).
The film can also be in the form of a discreet sheet, integrated with the substrate to be laminated or separate from the substrate to be laminated, or in continuous, web form. Discreet sheets are commonly used with pouches, e.g., drivers' licenses, school pictures, posters, etc. In “pouch-type” laminations, the film is integrated with the substrate to be laminated. Specifically, the film is hingedly adhered to an edge of the substrate, typically foam board. The integral film has a heat activated adhesive on the side of the film facing the substrate.
In continuous form, the film is supplied to the laminator from a supply roll and in web form. Usually, the web of film is fed to the laminating machine from a supply roll and the articles to be laminated are supplied to the machine individually. If the lamination is to be one-sided, the film is supplied from a single roll; if the lamination is to be two-sided, the film is supplied from two, separate rolls, one above the article to be laminated and one below the article to be laminated.
The coatings or adhesives used on these films incorporate vinyl acetate into the backbone of the polyethylene polymer. The resulting resin is an EVA (Polyethylene Vinyl Acetate copolymer) or form thereof. These adhesives are not tacky at room temperature, but become tacky when heat is applied to them, e.g., over 175° F.
As noted previously, for certain applications, such as presentations, advertisements, exhibits, educational training, etc., it is desirable to mount the substrate to be laminated onto a supportive backing, such as a rigid substrate or semi-rigid substrate (e.g., foam board, GATORBOARD®, PVC board, SYNTRA®, matt board, illustration board and cardboard (e.g., 24 pt. board)).
As noted previously, for certain applications, such as presentations, advertisements, exhibits, educational training, etc., it is desirable to mount the substrate to be laminated onto a supportive backing, such as a rigid or semi-rigid substrate (e.g., cardboard, foam board, GATORBOARD®, etc.). To simplify and clarify discussion, the item to be laminated will be called at times the “print substrate,” even though it does not necessarily need to be printed. In addition, the surface facing outwardly towards the viewer will be called the “front surface,” and the surface facing the backer board will be called the “back surface.”
FIGS. 5-11 generally show various processes used today. The laminator is generally shown by the reference number 30. It includes a pair of pressure rollers 101,102, a pair of film supply rollers 105,106 (for thermal laminated film (requiring heat) or PSA film (not requiring heat)), a pair of pull rollers 103,104 and at least one release liner rewind 107. Typically, a print substrate 200 is first laminated on its front surface (one-sided lamination) via a lamination process and then adhered, via its back surface, onto a rigid backer or substrate via a second lamination process. As such, it usually requires several passes through a laminating machine to laminate the print substrate to a backer board.
According to a first process, the print substrate 200 is first laminated on the front surface (top) with a thermal laminating film 201 and on the back surface (bottom) with a pressure sensitive mounting adhesive (PSA) (on film) 250 with a backing tape 251 (FIG. 5). The resulting product is a decaled print 201. The decaled print 201 is then fed through a laminating machine 30 (without the heat being turned on) abutting the backer board 300 while the backing tape 251 is pulled from the PSA 250 (FIG. 9). The backing tape 251 is removed before the substrates enter the nip rollers 101,102 so as to expose the adhesive to the backer board 300. The emerging product is the laminated print on a backing board 400.
According to a second process, the print substrate 200 is first laminated on the front surface (top) and the back surface (bottom) with a thermal laminating film 202 (FIG. 6). The emerging product is a two-sided laminate 204. The two-sided laminate 204 is fed into the same laminating machine or another laminating machine and is laminated on the back surface (bottom) with a pressure sensitive mounting adhesive (PSA) (on film) 250 with a backing tape 251 (FIG. 7). The resulting product is also a decaled print 201. The decaled print 201 is then fed through a laminating machine 30 (without the heat being turned on) abutting the backer board 300 while the backing tape 251 is pulled from the PSA 250 (FIG. 9). The emerging product is the laminated print on a backing board 400.
According to a third process, the print substrate 200 is laminated via an unheated laminator 30 on the back surface (bottom) with a with a pressure sensitive mounting adhesive (PSA) (on film) 250 with a backing tape 251 (FIG. 8). A first backing tape 252 is removed to adhere the PSA to the print substrate 200. The resulting product is yet another decaled print 201. The decaled print 201 is then fed through a laminating machine 30 (without the heat being turned on) abutting the backer board 300 while the backing tape 251 is pulled from the PSA 250 (FIG. 9). The emerging product is a print on a backing board 400.
According to a fourth process, the backer or mounting board 300 is laminated via a laminator 30 on the front surface (top) with a pressure sensitive mounting adhesive (PSA) (on film) 250 with a backing tape 251 (FIG. 10). The resulting product is a pre-coated mounting board 301. As shown in FIG. 11, a decaled print 202 (made according to the process shown in FIG. 6) is then fed through a laminating machine 30 (without the heat being turned on) abutting the pre-coated mounting/backer board 301 while the backing tape 251 is pulled from the PSA 250 (FIG. 11). The emerging product is the laminated print on a backing board 400.
As discussed above, it usually requires two passes through a laminating machine to laminate the print substrate to a backer board. It should be noted that in addition to being very time consuming, this has inherent problems. For example, the thicknesses of the print substrate (the first pass through the laminating machine) and the backer board with the print substrate (the second pass through the laminating machine) are quite different. Many laminating machines have thickness settings requiring a resetting of the machine with each change in thickness of the items to be laminated. As a result, an operator would be forced to change the machine's setting with each new pass through the machine. In addition, the adhesive used for the first pass through the laminating machine must succumb to the trauma of a second heating with applied pressure. This can cause additional problems such as wrinkles, unevenness, running of adhesive, etc.
Using pressure sensitive adhesives, e.g., substrates having an adhesive with a protective backing tape/sheet covering the adhesive, in the process or steps just described has its own problems. Suffice it to say that just the many steps of peeling off the protective backing, aligning the objects and adhering the objects together two or more times per product can be difficult and riddled with problems.
For example, U.S. Pat. No. 4,197,151 discloses a system for manually mounting a sheet-like article (with a pressure sensitive adhesive coating on both surfaces) onto a rigid substrate. The details outlined in this patent for performing this task speak to the difficulty of the process as a whole. In addition, it is questionable whether the teachings of this patent can be properly applied to large prints, such as banners.